Not OP, but I feel similarly and for me it's because the information assymmetry is a deliberate way to give advantage to the seller. I also perceive deliberate lack of transparency as dishonest and exploitative. If you can't give me a price upfront, I probably don't want to do business with you.

That may not be entirely fair, but that is my perception

I also don't like doing business with people I can't trust on a handshake.

Contracts IMO should really only formalize the implicit understanding of expected boundaries to be followed by both parties. If you're the type of person to seek advantage when an unexpected situation comes up, I don't really want to do business with you.